Supplementary Materials

Adhesion property measurements contribute to the comprehensive understanding of the mechanical properties of soft matters. Indentation tests are a common method for measuring adhesion force. However, indenters generally have a large volume and a small sensing angle and thus are not conducive to local detection in high-precision environments. Here, we propose a vision-based contact adhesion measurement (VisCAM) method and design a compact sensing device to measure the adhesion force of soft matters.The coupling of the 7.6 mm diameter device and a flexible fiber makes thesystem similar to a miniaturized endoscope. Classical contact theories and finite element models are used for the contact mechanics analysis of silicone rubber. The image grayscale–loading mathematical model is constructed based on the change in contact light spot. Finally, the uncertainty of the system is less than 4%, and the measurement error is 0.04 N. Our method provides better solutions for understanding the adhesion properties of soft matters.